1. Field of the Invention
The present invention relates to an image forming apparatus to which a container containing toner is mounted.
2. Description of the Related Art
An electrophotographic image forming apparatus develops an electrostatic latent image formed on a photosensitive member using a developer (hereinafter referred to as toner) in a developing unit to form a toner image. Since there is a limit to an amount of toner which can be stored in the developing unit, toner is supplied as appropriate to the developing unit from a container which is detachably mounted to the image forming apparatus main body.
Japanese Patent Application Laid-Open No. 2010-256893 discusses a container which includes the following. The container includes a rotation unit which is rotatably driven, a pump unit configured to change internal pressure of a containing unit containing toner to discharge the toner from the containing unit, and a conversion unit configured to convert rotational movement of the rotation unit to expansion and contraction movement of the pump unit. The container expands and contracts the pump unit according to rotation of the container to discharge the toner inside the container. More specifically, air taken in from a discharge port according to expansion of the pump unit loosens the toner inside the containing unit. The containing unit then enters a negative pressure condition according to contraction of the pump unit, and the air inside the container pushes out the toner covering the discharge port from the discharge port.
However, it is necessary to control a rotational speed of the above-described container with high precision to precisely control the amount of toner to be discharged from the container.